Question

Please help..

1. How do a star's temperature and size affect its appearance?
2. How is the electromagnetic spectrum used to examine astronomical objects?

Answer 1

1) When a star's temperature or size increases, its luminosity increases. In other words it seems more bright.

2) The electromagnetic spectrum is used to determine different types of light waves (infrared, visible light, x-rays etc.) which produced by different kinds of astronomical objects.